Revealing mistake: When the shark bursts through the window of the cabin, in each of the shots facing Brody, including when he shoves the air tank into the shark's mouth, the glistening water is visible in the window's reflection behind Brody. The shark's reflection is never seen behind Brody, despite the shark's massive size in the small cabin. Bruce must have had the day off during Roy Scheider's takes. (01:58:00)Super Grover
Revealing mistake: When the black guy is attacked after being let go, his throat is slashed. Check out how dreadfully fake the blood is. It looks like watered down ketchup.